1. Field of the Invention
The present invention relates to a medical retrieval instrument.
2. Description of the Related Art
Generally, in a medical retrieval instrument with a wire basket, forward and backward movement of an operation wire inserted into a sheath causes the wire basket mounted near the distal end of the sheath to open and close relative to the distal end of the sheath. The wire basket holds such objects as nephrolith or ureterolith or the like from a body cavity and then retrieves the object for inspection outside the body.
Japanese Utility Model Laid-Open Publication No.1-172813 discloses a medical retrieval instrument in which one end of a wire basket is connected to the distal end of an operation wire, whereas the other end of the wire basket is connected to the distal end of a sheath.
However, the medical retrieval instrument of this Japanese Utility Model Laid-Open Publication No.1-172813 has a problem. Unless one end of the wire basket is fixed to the distal end of the sheath precisely at a predetermined position and in a predetermined direction, the wire basket does not expand to a desired shape. As a result, a stone captured in the wire basket cannot be held efficiently.
Regardless of the above-mentioned problem, a medical retrieval instrument of the Japanese Utility Model Laid-Open Publication No.1-172813 has a wire basket, one end of which is only held by a ring-like holding tube and fixed to a sheath. Such a mounting configuration is unstable, since one end portion of the wire basket easily slips on the outer surface. Therefore, it takes more time to mount one end portion of the wire basket at a predetermined position and in a predetermined direction.